By the end of 1998, the C. elegans genome mapping and sequencing consortium will have completed almost the entire C. elegans sequence. The present proposal seeks to consolidate and build on the success of the past fifteen years through four specific aims: 1. the completion to high quality of any regions that remain incomplete and the validation of the fidelity of the sequence. 2. the creation of an Internet client-server system, based on ACeDB, to facilitate access to the data and to allow annotation of the sequence by all investigators; 3. the use of comparative sequencing, particularly C. briggsae genomic sequencing, to improve and enrich the interpretation of the C. elegans sequence; 4. the development of methods that will allow efficient, automatic descriptions of gene expression patterns. With the accomplishment of these four goals, we will set the stage for a much more complete understanding of how the C. elegans genome dictates the development, behavior, and other biology of this small but complex animal. In turn, the principles learned here should help to unlock the information stored in other animal genomes, including human.